Based on your example, the solution could look like this: (^09$|^9$|^7$) or shorter: ^(09|9|7)$ ... (bloody beginner in RegEx ) ...
On the website https://regex101.com/ you can readjust the example and on the right you will find explanations of the parameters.

2019-07-05_EmEditor_Multiple-line CTRL-ENTER Find_RegEx.png

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Personally, I would be interested to know if you or someone else knows how to perform an exact search for a number with RegEx.

Example:
1
2
3
09
09 blank 09 4
4
4 (Space before the number 4)
4 (Space(s) before and after the number 4)
24
5

(2|4|09) --> 24 is also found - unwanted!
[2|4|09] --> 24 is also found - unwanted!
(2+?|4+?|09+?) --> 24 is also found - unwanted!

Anybody have a solution?
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Regarding the variant CTRL + ENTER in the search window in EmEditor I'm still waiting for a reply in the EmEditor Forum.
After receipt I will give you the answer here.

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You can see that the normal search and search in many lines is practically no different, and it does not make this task any easier. But here we are talking only about regular expressions! What if I am looking for something in many lines without a regular expression? Multiline then does not apply here.

For me personally, I have noted the following as a brief summary *:
With CTRL + ENTER and option "Multiline" in the "Find"-window, it is possible to search for a cohesive search term over several lines.* Here is a detailed description of this function: https://www.emeditor.com/forums/topic/m ... post-25964

If something is not in EmEditor, it does not mean it can not be. From what I know, you can write "Macro" for "Undo All". Unfortunately, I do not have any knowledge of writing Macros. I proposed this function to the author of the program in 2017, he assured me that he would implement it sometime.

Rather, it's not the same, although I'm not sure if it works on all tabs. The author did not mention anything about it.